Electrospinning of ptfe with high viscosity materials

Abstract

An improved process for forming a PTFE mat is described. The process includes providing a dispersion with PTFE, a fiberizing polymer and a solvent wherein said dispersion has a viscosity of at least 50,000 cP. An apparatus is provided which comprises a charge source and a target a distance from the charge source. A voltage source is provided which creates a first charge at the charge source and an opposing charge at the target. The dispersion is electrostatically charged by contact with the charge source. The electrostatically charged dispersion is collected on the target to form a mat precursor which is heated to remove the solvent and the fiberizing polymer thereby forming the PTFE mat.

1 - 19 . (canceled) 
     
     
         20 . A nonwoven mat comprising a plurality of electrospun poly(tetrafluoroethylene) fibers, wherein the plurality of poly(tetrafluoroethylene) fibers exhibit uniform diameter. 
     
     
         21 . The mat of  claim 20 , wherein no beading is observed when the mat is subjected to visual examination under magnification. 
     
     
         22 . The mat of  claim 20 , wherein fewer than 20% of the plurality of electrospun poly(tetrafluoroethylene) fibers are in the form of broken fibers. 
     
     
         23 . The mat of  claim 20 , wherein the bubble point pore diameter is between about 2 microns and about 10 microns. 
     
     
         24 . The mat of  claim 20 , wherein the density of the mat is between about 2.0 g/cm 3 and about 2.3 g/cm 3 . 
     
     
         25 . A nonwoven mat comprising a plurality of electrospun poly(tetrafluoroethylene) fibers, wherein fewer than 20% of the plurality of electrospun poly(tetrafluoroethylene) fibers are in the form of broken fibers. 
     
     
         26 . The mat of  claim 25 , wherein the poly(tetrafluoroethylene) has an average molecular weight of about 10 6  Da to 10 8  Da. 
     
     
         27 . The mat of  claim 25 , wherein the bubble point pore diameter is between about 2 microns and about 10 microns. 
     
     
         28 . The mat of  claim 25 , wherein the density of the mat is between about 2.0 g/cm 3 and about 2.3 g/cm 3 . 
     
     
         29 . A nonwoven mat comprising a plurality of electrospun poly(tetrafluoroethylene) fibers, wherein the mat has a tensile strength normalized to 1 mil thickness, calculated by dividing measured tensile strength by thickness of the mat in mils, of about 45 psi or greater. 
     
     
         30 . The mat of  claim 29 , wherein the mat has a normalized tensile strength of between about 45 psi and about 1422 psi. 
     
     
         31 . The mat of  claim 29 , wherein the elongation to failure of the mat is about 100% or greater. 
     
     
         32 . The mat of  claim 29 , wherein the elongation to failure of the mat is between about 100% and about 200%. 
     
     
         33 . The mat of  claim 29 , wherein the plurality of poly(tetrafluoroethylene) fibers exhibit uniform diameter. 
     
     
         34 . The mat of  claim 29 , wherein the bubble point pore diameter of the mat is between about 2 microns and about 10 microns. 
     
     
         35 . The mat of  claim 29 , wherein the density of the mat is between about 2.0 g/cm 3 and about 2.3 g/cm 3 . 
     
     
         36 . The mat of  claim 29 , wherein fewer than 20% of the plurality of electrospun poly(tetrafluoroethylene) fibers are in the form of broken fibers.